The standard Ruby reflection does not provide for getting method parameter names (at least afaik), and the only other solution that I found is using parsetree, which is “more clean” then this method, but requires another gem…

So here it comes Monkey-Style:

def methods_with_parameters(klass, path_to_file)
  methods = klass.instance_methods(false).sort
  lines = File.read(path_to_file)

  #find params for methods
  methods.map do |method|
    lines.detect{|l|l=~/def #{method}(.*)$/}
    parameters = $1.tr('()','').split(',').map{|p| p.gsub(/=.*/, '')}.reject(&:blank?).map(&:strip)
    [method, parameters]
  end
end